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United States Patent |
5,547,009
|
Plumer
|
August 20, 1996
|
Driving and tensioning device for a flexible protective member such as a
strip, curtain or skirt
Abstract
A driving and tensioning device for a flexible protective member such as a
strip, curtain or skirt includes a rolling-up driving-shaft and an
unrolling driving-shaft which are driven by electric motors provided with
a brake activated in order not to brake any longer when one of these
motors is under power. This driving and tensioning device furthermore
includes a device for controlling the power supply to the motors so that a
torque is generated by one of the motors withstanding the operation of the
other motor, during the phase of either unrolling or rolling-up of the
flexible protective member.
Inventors:
|
Plumer; Louis (Belfort, FR)
|
Assignee:
|
Etablissments Bubendorff (Societe Anonyme) (Saint-Louis, FR)
|
Appl. No.:
|
311059 |
Filed:
|
September 23, 1994 |
Foreign Application Priority Data
Current U.S. Class: |
160/310; 160/265 |
Intern'l Class: |
A47G 005/02; A47H 001/00; E06B 009/56 |
Field of Search: |
160/310,265,314,133
|
References Cited
U.S. Patent Documents
2183495 | Dec., 1939 | Laufersweiler.
| |
2347845 | May., 1944 | Schane.
| |
4766941 | Aug., 1988 | Sloop et al. | 160/310.
|
4815515 | Mar., 1989 | Lee | 160/310.
|
5088543 | Feb., 1992 | Bilbrey | 160/265.
|
5249616 | Oct., 1993 | Yen | 160/310.
|
5355927 | Oct., 1994 | McKeon | 160/310.
|
Foreign Patent Documents |
0317461 | May., 1989 | EP.
| |
2502597 | Oct., 1982 | FR.
| |
2544887 | Oct., 1984 | FR.
| |
2303782 | Aug., 1974 | DE | 160/133.
|
2263729 | Aug., 1993 | GB.
| |
Other References
French Search Report.
|
Primary Examiner: Johnson; Blair M.
Assistant Examiner: Hamilla; Brian J.
Attorney, Agent or Firm: Greenblum & Bernstein P.L.C.
Claims
What is claimed is:
1. A driving and tensioning device for a flexible protective member and a
flexible protective member comprising one of a strip, a curtain, and a
skirt, said device comprising:
a rolling-up driving-shaft rolling said flexible protective member;
and an unrolling driving-shaft acting on said flexible protective member
for unfolding said flexible protective member;
each of said rolling-up driving-shaft and said unrolling driving-shaft
being each driven in rotation by a respective electric rolling and
unrolling motor;
said rolling and unrolling motors each associated with a respective braking
means, wherein said braking means do not brake when one of said rolling
and unrolling motors is activated;
said device further including means for controlling power supplied to said
motors to create a torque during a rolling and an unrolling operation,
wherein during said unrolling operation, said controlling means supplies a
reduced power to said rolling motor in a direction opposite an unrolling
direction, the reduced power to said rolling motor being less than a power
supplied to said unrolling motor, and
wherein, during said rolling operation, said controlling means supplies a
reduced power to said unrolling motor in a direction opposite a rolling
direction the reduced power to said unrolling motor being less than a
power supplied to said rolling motor.
2. The driving a tensioning device according to claim 1,
said flexible protective member comprising a strip with one of a horizontal
and a slightly inclined movement direction during said rolling up and said
unrolling operation;
said rolling-up driving-shaft and said unrolling driving-shaft being
positioned in parallel and said unrolling driving-shaft including drums
for rolling up respective straps forming a transmission means connected to
a free end of said flexible protective member.
3. The driving and tensioning device according to claim 1,
said flexible protective member comprising a skirt for roller blinds, said
skirt comprising of a plurality of blades connected to each other and
including openings capable of co-operating with a driving means associated
with said unrolling driving-shaft;
said unrolling driving-shaft positioned parallel and downstream with
respect to said rolling-up driving shaft.
4. The driving and tensioning device according to claim 1, said unrolling
driving-shaft being directly coupled to said flexible protective member.
5. The driving and tensioning device according to claim 1, said unrolling
driving-shaft being coupled to said flexible protective member through a
transmission means.
6. A driving and tensioning device for a flexible protective member, and a
flexible protective member comprising one of a strip, a curtain, and a
skirt, said device comprising:
a rolling-up driving-shaft for rolling said flexible protective member;
and an unrolling driving-shaft acting on said flexible protective member
for unfolding said flexible protective member;
each of said rolling-up driving-shaft and said unrolling driving-shaft
being driven in rotation by a respective electric rolling and unrolling
motor,
said rolling and unrolling motor each associated with respective braking
means wherein said braking means do not brake when one of said rolling and
unrolling motors is activated,
said device further including means for controlling power supplied to said
motors to create a torque during a rolling and an unrolling operation;
wherein, during said unrolling operation, said controlling means supplies a
reduced power to said unrolling motor in a direction of said unrolling
operation, said reduced power to said unrolling motor being less than a
power supplied to said rolling motor,
wherein, during said rolling operation, said controlling means supplies a
reduced power to said rolling motor in a direction of said rolling said
reduced power to said rolling motor being less than a power supplied to
said unrolling motor.
7. The driving and tensioning device according to claim 6,
said flexible protective member comprising a strip with one of a horizontal
and a slightly inclined movement direction during said rolling and said
unrolling operation;
said rolling-up driving-shaft and said unrolling driving-shaft being
positioned in parallel; and
said unrolling driving shaft including drums for rolling up respective
straps forming a transmission means connected to a free end of the
flexible protective member.
8. The driving and tensioning device according to claim 6,
said flexible protective member comprising a skirt for roller blinds, said
skirt comprising of a plurality of blades connected to each other and
including openings capable of cooperating with driving means associated
with said unrolling driving-shaft, and
said unrolling driving-shaft positioned parallel and downstream with
respect to said rolling-up driving-shaft.
9. The driving and tensioning device according to claim 6, said unrolling
driving-shaft being directly coupled to said flexible protective member.
10. The driving and tensioning device according to claim 6, said unrolling
driving-shaft being coupled to said flexible protective member through a
transmission means.
11. A driving and tensioning device for a flexible protective member, and a
flexible protective member comprising one of a strip, a curtain, and a
skirt, said device comprising:
a rolling-up driving-shaft for rolling said flexible protective member; and
an unrolling driving-shaft acting on said flexible protective member for
unfolding said flexible protective member;
each of said rolling-up driving-shaft and said unrolling driving-shaft
being each driven in rotation by a respective electric rolling and
unrolling motor;
said rolling and unrolling motor each associated with respective braking
means, wherein said braking means do not brake when one of said motors is
activated;
said device further including means for controlling power supplied to said
motors,
wherein during an initial phase of a rolling operation, said controlling
means supplies a reduced speed to said rolling motor and supplies nominal
power to said unrolling motor and in a direction of rolling said nominal
power to said unrolling motor producing a speed to said unrolling motor
less than the reduced speed supplied to said rolling motor, said reduced
speed supplied to said rolling motor being less than a speed supplied to
said rolling motor in a later phase of said rolling operation.
12. The driving and tensioning device according to claim 11,
said flexible protective member comprising a skirt for roller blinds, said
skirt comprising a plurality of blades connected to each other and
including openings capable of co-operating with driving means associated
with said unrolling driving-shaft.
13. The driving and tensioning device according to claim 11,
said flexible protective member shaped as a skirt for roller blinds, said
skirt comprising of a plurality of blades connected to each other and
including openings capable of co-operating with driving means associated
with said unrolling driving-shaft,
said unrolling driving shaft positioned parallel and downstream with
respect to the rolling-up driving shaft,
said driving device including, means for ensuring, from an initial phase of
rolling-up of said skirt, a theoretical linear speed for said skirt, said
speed of said rolling-up driving-shaft being greater than that of said
unrolling driving-shaft.
14. The driving and tensioning device according to claim 13,
said ensuring means are formed by said control means to respond to a
rotational speed of said unrolling motor associated with said unrolling
driving-shaft.
15. The driving and tensioning device according to claim 13,
said ensuring means being formed by a diameter of said rolling-up shaft
sufficient to achieve, under rotation of said rolling motor operating at
reduced power, a theoretical linear speed of said skirt higher than an
actual linear speed imparted to said skirt by said unrolling driving-shaft
during rotation of said unrolling motor at its nominal speed, during said
initial phase of rolling-up.
16. The driving and tensioning device according to claim 11, said unrolling
driving-shaft being directly coupled to said flexible protective member.
17. The driving and tensioning device according to claim 11, said unrolling
driving-shaft being coupled to said flexible protective member through a
transmission means.
Description
BACKGROUND OF THE INVENTION
1. Field of the Invention
The invention relates to a driving an tensioning device for a flexible
protective strip or curtain, comprising a rolling-up driving-shaft from
which and onto which unrolls and rolls up said protective strip, and an
unrolling driving-shaft acting on the flexible protective strip or curtain
for unfolding same, the rolling-up driving-shaft and the unrolling
driving-shaft being each driven in rotation by means of a motor associated
with braking means.
2. Description of the Prior Art
There is already known a driving device for a flexible protective strip or
curtain-type member meeting the above description. Thus, this driving
device includes a rolling-up driving-shaft from which and onto which
unrolls and rolls up the flexible member. This rolling-up driving-shaft is
driven in rotation through a tubular-type motor or the like, this during
this phase of rolling up of the flexible member. It should be noted that
this motor is provided with an electromagnetic brake which is activated,
i.e., it does no longer brake, when the motor it is associated with is in
operation, i.e., rolling up, but also during the phase of unfolding
controlled by the unrolling driving-shaft. As a matter of fact, like the
rolling-up driving-shaft, this latter cooperates with a motor which
ensures its driving in rotation during the phase of unfolding of the
protective member. Here too, with this motor is associated an
electromagnetic brake which is activated, i.e., which does no longer
brake, as soon as one of the motors of the rolling-up driving-shaft or
unrolling driving-shaft is under power.
Moreover, in this particular case, the rolling-up driving-shaft and the
unrolling driving-shaft are arranged parallel to each other on both sides
of the surface to be covered by means of the flexible protective member.
Furthermore, this latter is initially rolled up onto the rolling-up
driving-shaft and includes, at the height of its free end, straps joining
the unrolling driving-shaft where they roll up onto drums this latter is
provided with.
As a matter of fact, this kind of flexible protective member is aimed at
unfolding in a nearly horizontal or slightly inclined position above the
surface to be protected. Therefore, this raises the problem of the
tensioning of this flexible member and its maintaining in such a position.
Under its own weight, this flexible protective member indeed necessarily
sags between the rolling-up driving-shaft and the unrolling driving-shaft,
more particularly during the unfolding phase. It should indeed be reminded
that during the operation of one of the motors the brakes associated to
each of them are activated to enable free rotation of the rolling-up
driving-shaft and the unrolling driving-shaft.
Therefore, in order to take up the slack of the flexible protective member
upon unfolding, it is intended to control the operation, during a short
time, of either the motor of the unrolling driving-shaft or that of the
rolling-up drivingshaft. More particularly, during this short time, either
the rolling-up driving-shaft or the unrolling driving-shaft, as the case
may be, of the motor which is not activated is not driven in rotation
because of its inertia. Consequently, there occurs no additional unrolling
of either the protective member or the straps, but a mere taking up of the
slack at the level of this untensioned flexible protective member.
Consequently, upon the complete standstill of the motors, the brakes are
deactivated and impede rotation in any direction of this rolling-up
driving-shaft and the unrolling driving-shaft, to finally keep the
flexible protective member tensioned.
Practical experience shows that this process is not merely theoretical,
that is, for the process to work the backlash to be taken up to ensure the
tensioning of the flexible protective member should be small, for
otherwise the period of time during which one of the motors is actuated to
ensure this tensioning is either too short or too long, so that the
unrolling of said flexible protective member or the straps connected to
the unrolling driving-shaft cannot simultaneously be impeded.
In order to improve the driving device as described above, there has been
imagined to associate with the rolling-up driving-shaft, and auxiliary
brake capable of producing a torque withstanding the rotation of this
rolling-up driving-shaft during the unfolding of the protective member.
More particularly, through such a resisting couple the traction which has
to be exerted on the straps through the driving in rotation of the
unrolling driving-shaft is higher, so that the protective member is
maintained tensioned during its unfolding.
This auxiliary brake may be of a mechanical or Foucault-current type. As a
matter of fact, a Foucault-current brake is efficient as soon as there
exists a rotation. As a result, it can give rise to a slackening of the
protective member at the end of the unfolding stroke. Therefore, it only
partly solves the above-mentioned problem. A mechanical brake of the
friction type often integrates a ratchet wheel so as not to enter into
operation in a determined direction of rotation, i.e., in the direction of
rotation followed by the rolling-up phase. Such a mechanical brake which
provides a solution for the disadvantages experienced with a
Foucault-current brake, however, proves particularly complex and leads to
a substantial increase of the cost price of the driving device.
To this should be added that if one not only wants to ensure that the
flexible protective member be tensioned when in unfolded position, but
also that the straps be so once said flexible protective member has been
completely or partially rolled up, it is necessary to provide both the
rolling-up driving-shaft and the unrolling driving-shaft with such an
auxiliary brake. One may of course imagine to combining the systems so
that, after rolling-up of the flexible protective member, the motions are
inverted for a short period of time by a control of the rotation of the
unrolling driving-shaft, in order to obtain the tensioning of the straps.
As a result, these solutions are uneconomical in one case and unpractical
to be used in the other case.
Such problems of tensioning, or more particularly of keeping tensioned, are
also experienced with respect to flexible protective members, of the
roller blind type, the skirt of which has a nearly horizontal movement or
at least with an insufficient slanting for its unfolding to occur under
its own weight.
By way of an example, such a roller blind includes a rolling-up
driving-shaft for the skirt rotatingly mounted in a box inside which is
also fitted the unrolling driving-shaft for this skirt. As a matter, this
latter is arranged below the rolling-up driving-shaft and includes, at its
ends, tooth wheels engaging into openings provided for at the ends of the
blades said skirt is comprised of. Thus, during the unfolding, the
unrolling driving-shaft is driven in rotation through a motor which is
associated to same. It also includes a brake which is activated, i.e.,
which does not brake when the motor is actuated and, conversely, impedes
the unrolling driving-shaft from rotation in the event the motor stops
operating, so as to lock in down movement the skirt of the roller blind.
The brake is also activated so as not to brake any longer during the
driving in rotation of the rolling-up driving-shaft through the motor
which is particular to same. In this kind of configuration, this
rolling-up driving-shaft for the skirt is often without electromagnetic
brake. As already stated, the locking of the skirt is indeed obtained
through the braking motor the unrolling driving-shaft is fitted with.
Therefore, the rolling-up driving-shaft is not subjected to a large torque
corresponding to the total weight of the skirt.
In addition, the motor of this rolling-up driving-shaft is associated with
auxiliary braking means. Thus, the reduction gear provides a braking force
capable of opposing the rotation of the rolling-up shaft under the
influence of the reduction torque produced by the few blades of the skirt
between the unrolling driving-shaft and that rolling-up driving-shaft.
As already stated above, the skirt of such roller blinds is made of a
juxtaposition of blades which are not only hingedly jointed to each other,
but are often also telescopic in a direction which is perpendicular to
same, so as to be capable of imparting to the skirt an openwork position.
More particularly, when the blades are kept separated from each other,
they leave openings allowing light rays to pass through. As a matter of
fact, this kind of telescopic jointing of the blades of a roller-blind
skirt gives rise to large difficulties, in particular within the framework
of roller blinds with nearly horizontal unfolding. More particularly, such
roller blinds are applied to roof windows or the like. Therefore, they are
particularly exposed to the elements. Thus, despite the presence of ta
protective box, moisture can penetrate into the joints of the blades
located inside this box and, of the blades extending between the
rolling-up driving-shaft and the unrolling driving-shaft. Now, in the
event of frost, this moisture becomes ice which clamps the joints of these
blades, while it is just between this rolling-up driving-shaft and the
unrolling driving-shaft that said joint is normally under highest strain.
Therefore, when the user tries to actuate its roller blind under these
circumstances, the skirt often brakes at the level. It should be noted
that these breaks only occur in the event two successive blades are kept
substantially edge to edge, in which position they can no longer pivot
with respect to each other.
This means that the blades of the skirt length between the rolling-up
driving-shaft and the unrolling driving-shaft should be kept steadily
apart so that they can at any time pivot with respect to each other,
whereby they impede the frost from immobilizing them in an edge-to-edge
position.
In addition, since the rolling-up of the skirt is achieved only under the
driving in rotation of the rolling-up driving-shaft, the motor must
necessarily have a sufficient torque, so as to be able to compensate for
the torque produced by total weight of the skirt. Now, this excessive
torque is a handicap in the event of clamping of the skirt, e.g., in its
upper portion, accommodated in the box. Since it is higher than the
mechanical strength of the skirt, it can indeed lead to the breaking of
this latter.
Finally, one should note that in order to deliver this high power, the
motor should be of an appropriate size. It is therefore also relatively
expensive. It is therefore cheaper to adapt the power of the motor to the
size of the roller blinds rather than using a standard motor for a series
of roller blinds. This does not avoid that this solution, adopted so far,
makes stiffer the control of the manufacturer and that of the stocks.
SUMMARY OF THE INVENTION
The scope of this invention is just to provide a solution for the
disadvantages experienced in the above-mentioned cases, this by means of
simple solutions which implement standard and consequently cheaper
material.
For this purpose, the invention relates to a driving and tensioning device
for a flexible protective member such as a strip, curtain or skirt,
comprising a rolling-up driving-shaft from which and onto which unrolls
and rolls up said flexible protective member, and an unrolling
driving-shaft acting this latter, either directly or through transmission
means, for unfolding same. The rolling-up driving-shaft and the unrolling
driving-shaft are each driven in rotation by means of a motor, and each
motor is associated with braking means activated in order not to brake
when one of the motors is actuated. This device furthermore including
means for controlling the power supply to the motors capable of ensuring
the operation, at reduced power and in the opposite direction with respect
to the actuation, of the motor of the rolling-up driving-shaft or of the
unrolling driving-shaft, when the device is in in the rolling-up or
unrolling phase, respectively, to create a torque withstanding this
actuation controlled by the operation of the motor, respectively, of the
unrolling driving-shaft or rolling-up driving-shaft.
The invention also relates to a driving and tensioning device for a
flexible protective member such as a strip, curtain or skirt, comprising a
rolling-up driving-shaft from which and onto which unrolls and rolls up
said flexible protective member, and an unrolling driving-shaft acting
onto this latter, either directly or through transmission means, for
unfolding same, the rolling-up driving-shaft and the unrolling
driving-shaft being each driven in rotation by means of a motor with which
are associated braking means activated in order not to brake any longer
when one of these motors is under power, this device furthermore including
means for controlling the power supply to the motors capable of ensuring
the operation, at reduced speed and in the same direction as the
actuation, of the motor of the rolling-up driving-shaft or of the
unrolling driving-shaft, according to one being in the rolling-up or
unrolling phase, respectively, to create a torque withstanding this
actuation controlled by the operation of the motor or of the unrolling
driving-shaft, respectively of the rolling-up driving-shaft.
Finally, the invention relates to a driving and tensioning device for a
flexible protective member such as a strip, curtain or skirt, comprising a
rolling-up driving-shaft from which and onto which unrolls and rolls up
the flexible protective member, and an unrolling driving-shaft acting onto
this latter, either directly or through transmission means, for unfolding
same the rolling-up driving-shaft and the unrolling driving-shaft being
each driven in rotation by means of a motor with which are associated
braking means eventually activated in order not to brake any longer when
one of these motors is under power, this device furthermore including
means for controlling the power supply to these motors capable of
enduring, at least during the rolling-up phase, the operation, on the one
hand, of the motor of the rolling-up driving-shaft at reduced speed and,
on the other hand, of the motor of the unrolling driving-shaft at it
nominal power and in the direction of the actuation.
The advantages achieved by means of this invention mainly reside in that it
is possible to maintain the tension of the flexible protective member,
without having recourse to auxiliary braking means which are often
complex, and consequently, expensive. Furthermore, the unfolding or
rolling-up controls of the flexible member occur with great ease in that
it is not necessary, in the event of stopping of the unfolding or
rolling-up control of this flexible member, to ensure the temporary
operation of this or that motor to achieve the tensioning of either the
flexible member itself or the straps which are associated to same.
In addition, the maintaining of the tensioning at the level of the flexible
member, such as a skirt of a roller blind for a roof window or the like,
this between the rolling-up driving-shaft and the unrolling driving-shaft
solves to a large extent the drawbacks experienced at that level and in
the even of frost which such roller blinds. In addition by combinedly
controlling the operation of the motors, one avoids, in the framework of
an application to such roller blinds, the use of an overpowered motor to
ensure the rolling-up of the skirt onto the rolling-up driving-shaft, this
latter being capable of being assisted during this operation by the motor
of the unrolling driving-shaft. This allows to provide a solution for the
problem of the breaking of the skirt usually caused by a such overpowered
motors.
Finally, by relieving the effort produced by the motor of the rolling-up
driving-shaft further to the assistance provided by the motor of the
unrolling driving-shaft, one notices that it can also be contemplated to
go toward a standardization of these motors. Indeed, for reasons of
manufacturing costs, which are lesser in the framework of a mass
production, the motors are preferably chosen of identical characteristics.
BRIEF DESCRIPTION OF THE DRAWINGS
The understanding of this invention will be made easier with reference to
the attached drawing in which:
FIG. 1 is a schematical perspective view of a driving and tensioning device
for a flexible protective member such as a strip or curtain which unfolds
nearly horizontally,
FIG. 2 is a schematical perspective view of a driving and tensioning device
for a flexible protective member in the shape of a roller blind skirt
applicable e.g. to roof windows or the like.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
As shown in the Figures of the attached drawing, this invention relates to
a driving and tensioning device 1 for a rolling-up flexible protective
member 2 such as a strip or curtain 3 as shown in FIG. 1 or such as a
skirt 4 for a roller blind as shown in FIG. 2.
As a matter of fact, this driving and tensioning device 1 is aimed at
ensuring the horizontal unfolding, or with a slight slant, of this
flexible protective member 2. Therefore, it includes first of all a
rolling-up driving-shaft 5 from which and onto which unrolls and rolls up
the flexible protective member 2. It furthermore comprises an unrolling
driving-shaft 6 acting onto this flexible protective member 2, either
directly, as shown in FIG. 2, or through transmission means 7, e.g.,
straps, corresponding to the embodiment of FIG. 1, for unfolding the same.
When referring more particularly to the embodiment shown in FIG. 1 showing
a driving and tensioning device for a flexible protective member 2 such as
a strip or curtain 3, the unrolling driving-shaft 6 is arranged parallel
to the rolling-up driving-shaft 5 and is located, with respect to this
latter, on the other side of the surface 8 to be covered and protected.
Onto this unrolling driving-shaft 6 are fitted drums 9, 10 onto which roll
up straps forming the transmission means 7 connected to the free end 11 of
the flexible protective member 2. The rolling-up driving-shaft 5 and the
unrolling driving-shaft 6 are each driven in rotation by means of an
electric motor 12, 13, respectively, which, as shown, may be of the
tubular type or even installed at the end of the shaft. With each of these
motors 12, 13 are associated braking means 14, 15, comprised, e.g., of an
electromagnetic-type brake. This brake 14, 15 is activated, i.e., it does
not brake, when any one of the motors 12, 13 is under power. Thus, in the
event these motors 12, 13 stand still the brakes 14, 15 are deactivated so
that the rolling-up driving-shaft 5, and the unrolling driving-shaft 6,
respectively, is locked from rotation.
According to a feature of the invention, the driving and tensioning device
1, within the framework of the embodiment shown in FIG. 1, includes means
16 for controlling the power supply of these motors 12, 13 capable of
ensuring the operation, at reduced power and in the opposite direction
with respect to the actuation being carried out of the motor 12, 13 of the
rolling-up driving-shaft 5 or the unrolling drivingshaft 6, according to
whether one passes into the unfolding or rolling-up phase, respectively,
of the flexible member 2. Thus, by way of an example, during the unfolding
phase, not only is the motor 13 under power so as to drive in rotation the
unrolling driving-shaft 6, causing the transmission means 7 to roll up
onto the drums 9, 10, but also the motor 12 of the rolling-up
driving-shaft 5, however at reduced power and in the opposite direction
with respect to the actuation being carried out, i.e., the unfolding of
the flexible member 2. Thus, this motor 12, which operates reversely,
generates a torque withstanding the actuation controlled by the operation
of the motor 13 of the unrolling driving-shaft 6. This situation is the
same, however reversed, during the phase of folding-up of the flexible
member 2. In this case, the motor 12 of the rolling-up driving-shaft 5 is
normally supplied with power while the motor 13 of the unrolling
driving-shaft 6 is supplied with reduced power and operates reversely with
respect to the actuation, in order to generate a resisting torque.
This resisting torque can also be achieved by ensuring the operation of the
motor 12, 13 in the same direction as the actuation being carried out, but
at a lower speed than that of the motor 13, 12, respectively, according to
whether one is unfolding or folding up the flexible member 2.
One should observe that within the framework of this embodiment according
to the invention, the power of the motors 12, 13 may be more reduced,
since these latter mutually assist each other during the various
actuations.
In all cases, whether under the action of a reduced-power supply to the
motors tending to have them rotate in the opposite direction with respect
to the actuation being carried out or under the action of a slower
rotation speed of one of these motors 12, 13 with respect to the other 13,
12, respectively, according to whether one is in the unfolding or
folding-up phase, respectively, the so produced resisting torque at the
level of the rolling-up driving-shaft 5 or of the unrolling driving-shaft
6 guarantees the maintaining tensioned of the flexible member 2 both
during the actuations and at the standstill of these motors 12, 13.
Consequently, one observes that through simple means for controlling the
operation of these motors 12, 13 and this without auxiliary brake or the
like, it is possible to guarantee a perfect tensioning of a flexible
member 2 both during and after the actuation.
Within the framework of a more particular application to a flexible member
2 such as a skirt 4 of a roller blind, one observes that the unrolling
driving-shaft 6 is located parallel to and substantially downstream with
respect to the rolling-up driving-shaft 5 from and onto which rolls up the
skirt 4. It should be noted that this latter is designed by a
juxtaposition of blades 17 connected to each other by means of hinged
joints often of a telescopic nature.
It should be noted that during the unfolding the ends of these blades 17
and consequently of the side edges 18, 19 of the skirt 4 move in guiding
rails 20, 21.
In this particular case, the unrolling driving-shaft 6, being arranged
downstream with respect to the rolling-up driving-shaft, directly acts
onto the blades 17 of the skirt 4 of the flexible member 2. As a matter of
fact, this unrolling driving-shaft 6 includes, at its ends, driving means
22, 23 in the shape of toothed wheels cooperating with the blades 17 and
engaging into openings 24 made at the level of the ends of these latter.
Here too, in order to maintain a certain tensioning between the blades 17
when they enter the area between the rolling-up driving-shaft 5 and the
unrolling driving-shaft 6, means 16 for controlling the power supply to
the motors 12, 13 associated with this rolling-up driving-shaft 5 and the
unrolling driving-shaft 6, respectively, may guarantee the power supply at
reduced power and in the opposite direction with respect to the actuation
being carried out during the unfolding and the folding-up, respectively,
of the flexible member 2.
Thus, by way of an example, during the folding up of this flexible member
2, the motor 12 of the rolling-up driving-shaft 5 is appropriately
supplied with power, while the motor 13 of the unrolling driving-shaft 6
is supplied with reduced power and in the opposite direction so as to
produce a torque withstanding the folding-up control of the flexible
member 2.
However, one observes that within the framework of such a control of the
operation of the motors 12, 13 and, e.g., during the folding-up of the
flexible member 2, the motor 12 associated with the rolling-up
driving-shaft 5 should have a power not only sufficient to face the total
weight of the skirt 4, but in addition to mitigate the resisting torque
generated by the motor 13 of the unrolling driving-shaft 6.
Therefore and according to the invention, it is intended more particularly
within the framework of such an application to a roller blind and during
the phase of rolling up of the skirt, to ensure through control means 16
the operation of the motor 13 in the same direction as the actuation being
carried out, but at reduced speed compared to the motor 12 acting onto the
rolling-up driving-shaft 5. It is obvious that under such circumstances
the motor 13 operating at reduced speed controls the speed rate of the
skirt 4 and cause a tensioning at the level of the skirt 4, more
particularly in the area between the unrolling driving-shaft 6 and the
rolling-up driving-shaft 5. Therefore, the blades 17 the skirt 4 are
steadily kept apart from each other so as to release their hinged joint.
As a matter of fact, this solution consisting in having the motors 12, 13
rotate in the same direction during an unfolding actuation, or more
particularly a folding-up, of the skirt 4 has the advantage that these
motors 12, 13 mutually assist each other during these various actuations.
This means that with a motor of a given power one is capable of unfolding
or rolling up a larger and heavier skirt compared to a prior situation. IN
a short word, this means that motors of a given power are capable of
meeting a larger range of roller blinds. Finally, this standardization of
the motors contributes to a large extent to a reduction of the cost price
of such a roller blind.
It should however be observed that electrical or electronic means for
controlling the rotation speed of motors, e.g., asynchronous motors, often
used in this field have a non-neglectible cost price. It is more
economical to use control means for the power supply to the motors in the
shape of power regulators. Thus, achieving the intended result i.e.,
maintaining tensioned the length of the skirt 4 between the rolling-up
driving-shaft 5 and the unrolling driving-shaft 6, there is contemplated
according to the invention to use means 16 for controlling the power
supply to the motors 12, 13 capable of ensuring, at least during the
rolling-up phase, the operation of, on the one hand, the motor 12 of the
rolling-up driving shaft 5 at reduced power and, on the other hand, of the
motor 13 of the unrolling driving-shaft 6 at nominal power and in the
direction of the actuation, i.e., in the direction of rolling-up of the
skirt 4.
It is however desirable to ensure, under these circumstances, that the
theoretical linear speed imparted to the skirt 4 by the rolling-up
driving-shaft 5 be systematically higher than the actual linear speed
imparted to this skirt 4 through the unrolling driving-shaft 6. As a
matter of fact, by using motors 12, 13 of identical characteristics, the
problem actually arises only during the initial phase of rolling-up of the
skirt 4 onto the rolling-up driving-shaft 5. During this phase it is
indeed necessary to ensure that the blades 17 of the skirt 4 be kept apart
from each other so that their respective hinged joints be released and
that they be capable of rolling up onto the rolling-up driving-shaft 5
while resting on same. Consequently, by ensuring that the theoretical
linear speed liable of being imparted to the skirt 4 by the rolling-up
driving-shaft 5 right from the initial phase of this rolling-up is higher
than the linear speed liable of being imparted to the skirt 4 through the
unrolling driving-shaft 6, one is sure that a tensioning is steadily
exerted onto the skirt 4 between this rolling-up driving-shaft 5 and the
unrolling driving-shaft 6, which tensioning leads to the separation of the
blades 17 from each other. It is obvious that this theoretical linear
speed imparted to the skirt 4 through the rolling-up driving-shaft 5
progressively increases as the skirt forms windings about this rolling-up
driving-shaft 5.
To achieve the above result, the present invention may adapt the rotation
speed of the motor 13 through control means 16 while ensuring through same
the operation at reduced power of the motor 12 associated with the
rolling-up driving-shaft 5. This solution has however the disadvantage of
complicating the configuration of the control means 16 and as a result of
making them particularly expensive. As a matter of fact, an advantageous
solution consists in choosing a sufficiently large diameter for the
rolling-up driving-shaft 5, i.e. which right from the initial phase of
rolling up allows to ensure, under the action of the rotation of the motor
12, a theoretical linear speed of the skirt 4 which is higher than the
actual linear speed imparted to this skirt 4 through the unrolling
driving-shaft 6 and thus the motor 13. More particularly, the diameter of
the toothed wheels 23 the unrolling driving-shaft 6 is fitted with at its
ends and which engages into the openings 24 provided in the skirt 4.
It should be stated that within the framework of such an application to a
roller blind the braking means 14, 15 associated with the motor 12, 13 can
be formed, like within the framework of the preceding embodiment, by an
electromagnetic brake directly coupled to each of these motors 12, 13.
However, because of the small distance between the rolling-up
driving-shaft 5 and the unrolling driving-shaft 6, it is in fact enough to
associate such an electromagnetic brake only with the motor 13 of the
unrolling driving-shaft 6, this mainly in order to guarantee the locking
of the skirt 4 in any position and that it will not automatically unfold
under its own weight. Braking means directly depending on the
configuration of the motor 13 and speed-regulator-type driving means
associated to the same are in this case indeed sufficient to maintain
tensioned the blades of the skirt length between the rolling-up
driving-shaft 5 and the unrolling driving-shaft 6 after standstill of the
motors 12, 13.
To conclude, as this appears from the above description, this invention not
only provides a solution for a real technical problem regarding the
horizontal unfolding, or with a slight slant, of a flexible protective
member, but in addition, thanks to its simplicity, proves to be of a
reduced cost price and allows some standardization at the level of the
manufacturing. Therefore, this invention represents a clear technical
progress in the field concerned.
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